Abstract

Introduction

The aim of this study was to determine the prevalence of gastrointestinal and behavioural
symptoms occurring before (anticipatory/associative) and after methotrexate (MTX)
administration, termed MTX intolerance, in rheumatoid (RA) and psoriatic arthritis
(PsA).

Methods

Methotrexate Intolerance Severity Score (MISS), previously validated in juvenile idiopathic
arthritis patients, was used to determine MTX intolerance prevalence in 291 RA/PsA
patients. The MISS consisted of four domains: abdominal pain, nausea, vomiting and
behavioural symptoms, occurring upon, prior to (anticipatory) and when thinking of
MTX (associative). MTX intolerance was defined as ≥6 on the MISS with ≥1 point on
anticipatory and/or associative and/or behavioural items.

Results

A total of 123 patients (42.3%) experienced at least one gastrointestinal adverse
effect. The prevalence of MTX intolerance was 11%. MTX intolerance prevalence was
higher in patients on parenteral (20.6%) than on oral MTX (6.2%) (p < 0.001).

Conclusion

Besides well-known gastrointestinal symptoms after MTX, RA and PsA patients experienced
these symptoms also before MTX intake. RA and PsA patients on MTX should be closely
monitored with the MISS for early detection of MTX intolerance, in order to intervene
timely and avoid discontinuation of an effective treatment.